The present invention relates to a packing material for solid phase extraction, having a hydrophobic group and an ion exchange group within a particle, and also relates to a solid phase extraction method, a packing apparatus and a method for treating a sample, using the packing material.
A liquid-liquid extraction method has been heretofore used for extracting a sample from a liquid in many cases, however, this method has a problem in that the operation is cumbersome, a large amount of a solvent is used and the solvent used greatly affects the environment and the human body. At present, with the progress of synthesis methods, a solid phase extraction method using silica-based or synthetic polymer-based porous particles is used, where the operation is simple, the amount of solvent used is small and a large amount of sample can be automatically treated.
The packing material for use in the solid phase extraction includes those using an inorganic substrate, such as chemical bond-type silica gel where the surface of silica gel is subjected to a chemical modification with an octadecyl group to render the surface of the packing material hydrophobic, and those using an organic substrate, such as synthetic polymer represented by styrene-divinylbenzene. These packing materials utilize a hydrophobic interaction between the hydrophobic group of the packing material and the hydrophobic group of a sample, and therefore, are not suitable for the pretreatment operation of an ionic substance.
Accordingly, an ion exchange resin has been used for the operation of pretreating an ionic substance by solid phase extraction, however, since the ion exchange resin is obtained by introducing an ion exchange group into the surface of silica gel or a hydrophilic synthetic polymer or by introducing an ion exchange group into a hydrophobic substrate resin to change the property thereof to be extremely hydrophilic, the interaction between the packing material and a sample is only an ion exchange activity.
As such, in the case of conventional packing materials for solid phase extraction, the hydrophobic interaction or ion exchange activity of the packing material particle is used independently and studies have not been satisfactorily made on a packing material particle for solid phase extraction having different properties at the same time.
An object of the present invention is to obtain a packing material having excellent capabilities by studying conventional packing materials for solid phase extraction each having a property of bringing about a hydrophobic interaction or ion exchange activity independently, and a packing material having a hydrophobic site and an ion exchange site at the same time within a particle.
As a result of continuous and extensive investigations to overcome the above-described problems, the present inventors found that a packing material for solid phase extraction ensuring excellent recovery of samples including a hydrophobic substance and an ion exchange substance can be obtained by introducing an ion exchange site while not impairing the hydrophobic site within a particle, thereby having both properties. The present invention has been accomplished based on this finding.
More specifically, the present invention relates to the following embodiments.
[1] A packing material for solid phase extraction, comprising a synthetic polymer obtained by copolymerizing a hydrophobic monomer (A) and a hydrophilic monomer (B) and introducing thereinto an ion exchange group by a chemical modification.
[2] The packing material for solid phase extraction as described in [1] above, which contains an aromatic divinyl compound as the hydrophobic monomer (A) in an amount of 30% by mass or more based on the total amount of monomers.
[3] The packing material for solid phase extraction as described in [1] or [2] above, which contains an N-vinylcarboxylic acid amide as the hydrophilic monomer (B) in an amount of 5 to 60% by mass based on the total amount of monomers.
[4] The packing material for solid phase extraction as described in [3] above, wherein the N-vinylcarboxylic acid amide is N-vinyl-2-pyrrolidone or N-vinylacetamide.
[5] The packing material for solid phase extraction as described in any one of [1] to [4] above, which contains a (meth)acrylic acid ester of a polyhydric alcohol having a hydroxyl group as the hydrophilic monomer (B) in an amount of 10% by mass or more based on the total amount of monomers.
[6] The packing material for solid phase extraction as described in [5] above, wherein the (meth)acrylic acid ester of a polyhydric alcohol having a hydroxyl group is glycerol dimethacrylate.
[7] The packing material for solid phase extraction as described in any one of [1] to [6] above, wherein the ion exchange group is introduced by covalent bonding.
[8] The packing material for solid phase extraction as described in any one of [1] to [7] above, wherein the ion exchange group covalently bonded is a sulfo group or a quaternary ammonium.
[9] The packing material for solid phase extraction as described in any one of [1] to [8] above, wherein the amount of the ion-exchange group covalently bonded is 5xcexc-equivalent or more based on 1 dry gram of the packing material.
[10] The packing material for solid phase extraction as described in any one of [1] to [9] above, which is used by packing it in a packing apparatus.
[11] The packing material for solid phase extraction as described in [10] above, wherein the packing apparatus is a column, a cartridge or a reservoir.
[12] The packing material for solid phase extraction as described in any one of [1] to [11] above, which is used for concentrating an objective component and/or removing impurities or contaminants.
[13] The packing material for solid phase extraction as described in any one of [1] to [12] above, which has an average particle size of 1 to 200 xcexcm.
[14] A method comprising using the packing material for solid phase extraction described in any one of [1] to [13] above in solid phase extraction employing a column switching method.
[15] A column for solid phase extraction, which is packed with the packing material for solid phase extraction described in any one of [1] to [13] above.
[16] A cartridge for solid phase extraction, which is packed with the packing material for solid phase extraction described in any one of [1] to [13] above.
[17] The column for solid phase extraction as described in [15] above, which is used for concentrating an objective component and/or removing impurities or contaminants.
[18] The cartridge for solid phase extraction as described in [16] above, which is used for concentrating an objective component and/or removing impurities or contaminants.
[19] A solid phase extraction method for an environment-related, medical or biological sample, which uses the column for solid phase extraction described in [15] or [17] above.
[20] A solid phase extraction method for an environment-related, medical or biological sample, which uses the cartridge for solid phase extraction described in [16] or [18] above.
[21] The method as described in [19] above, which is performed for the purpose of identification or quantification of a drug sample in serum.
[22] The method as described in [20] above, which is performed for the purpose of identification or quantification of a drug sample in serum.